Organic light emitting device and method of fabricating the same

ABSTRACT

An organic light emitting device and a method of fabricating the same includes a first substrate; a thin film transistor (TFT) on the first substrate; a planarization layer on the TFT; an organic light emitting diode (OLED) on the planarization layer; a passivation layer on the OLED; a second substrate on the passivation; and a hydrogen capturing material between the first and the second substrates to prevent oxidation of materials forming the TFT.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2013-0123631, filed on Oct.16, 2013, which is incorporated by reference for all purposes as iffully set forth herein.

BACKGROUND Field of the Disclosure

The present disclosure relates to an organic light emitting device and amethod of fabricating the same.

Description of the Prior Art

An organic light emitting device emits light using anelectroluminescence phenomenon in which an organic compound placedbetween electrodes emits light when electric current flows between theelectrodes. Further, an organic light emitting display device is adevice for displaying an image by controlling an amount of electriccurrent flowing to the organic compound to adjust an amount of emittedlight.

The organic light emitting display device has an advantage in that it ispossible to make it light weight and thin while emitting light using athin organic compound between the electrodes.

In the case that the organic light emitting device is driven by an oxidethin film transistor (TFT), if a characteristic of the oxide is changeddue to various factors, a change in electric behavior of the transistormay cause a threshold voltage shift. If the extent of the thresholdvoltage shift is outside a compensation range for a circuit driving anorganic light emitting panel, the threshold voltage shift may result ina stain or a deviation of luminance that may be visible on the screen.

Accordingly, the threshold voltage shift may be an important factorcausing degradation of the organic light emitting display device, andmay limit use of the oxide thin film transistor in driving the displaydevice.

SUMMARY

Accordingly, this disclosure is directed to an array substrate includingan organic light emitting display device that substantially obviates oneor more of the problems due to limitations and disadvantages of therelated art.

An object of the disclosure is to provide an organic light emittingdevice including a hydrogen capturing material that is capable ofefficiently improving reliability of a driving TFT and displayperformance.

Additional features and advantages of the disclosure will be set forthin the description which follows, and in part will be apparent from thedescription, or may be learned by practice of the disclosure. These andother advantages of the disclosure will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the referenced drawings.

To achieve these and other advantages and in accordance with the purposeof the disclosure, as embodied and broadly described, an organic lightemitting device comprising: a first substrate; a thin film transistor(TFT) on the first substrate; a planarization layer on the TFT; anorganic light emitting diode (OLED) on the planarization layer; apassivation layer on the OLED; a second substrate on the passivation;and a hydrogen capturing material between the first and the secondsubstrates.

In another aspect, a method of fabricating an organic light emittingdevice comprising the steps of: preparing a first substrate; forming athin film transistor (TFT) on the first substrate; forming aplanarization layer on the TFT; forming an organic light emitting diode(OLED) on the planarization layer; forming a passivation layer on theOLED; disposing a second substrate on the passivation; and forming ahydrogen capturing material between the first and the second substrates.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating a system configuration of an organic lightemitting display device to which exemplary embodiments may be applied;

FIG. 2 is a sectional view schematically illustrating an organic lightemitting device according to a first exemplary embodiment;

FIG. 3 is a sectional view illustrating an organic light emitting deviceaccording to a second exemplary embodiment;

FIG. 4A is a perspective view illustrating a body centered cubic latticeconfiguration of a single metal foil constituting a second substrate;

FIG. 4B is a perspective view illustrating a face centered cubic latticeconfiguration of the single metal foil constituting the secondsubstrate;

FIG. 5A is a perspective view illustrating a body centered cubic latticeconfiguration of a metal foil alloy constituting a second substrate;

FIG. 5B is a perspective view illustrating a face centered cubic latticeconfiguration of the single metal foil alloy constituting the secondsubstrate;

FIGS. 6A to 6D are sectional views illustrating a mechanism in whichresidual hydrogen generated during a device process is captured in ametal foil or a metal foil alloy having a lattice configuration;

FIG. 7A is a sectional view illustrating a general organic lightemitting device in which residual hydrogen is diffused throughout anoxide thin film transistor so as to shift a threshold voltage of theoxide thin film transistor;

FIG. 7B is a sectional view illustrating an organic light emittingdevice in which residual hydrogen is diffused into a second substrateaccording to the second exemplary embodiment of FIG. 3;

FIG. 8 is a flowchart illustrating a process of fabricating an organiclight emitting device according to the second exemplary embodiment;

FIGS. 9A to 9D are sectional views illustrating an organic lightemitting device in sequence of processes of fabricating the organiclight device according to a third exemplary embodiment;

FIG. 10 is a sectional view illustrating an organic light emittingdevice according to the third exemplary embodiment;

FIGS. 11A to 11D are sectional views illustrating an organic lightemitting device in sequence of processes of fabricating the organiclight emitting device according to the third exemplary embodiment;

FIG. 12 is a sectional view schematically illustrating an organic lightemitting device according to a fourth exemplary embodiment; and

FIG. 13 is a graph illustrating a variation of a content of hydrogen ina second substrate when the organic light emitting device of FIG. 3including the second substrate is made of a metal foil alloy which is ametal foil based hydrogen capturing metal and includes a hydrogenresolving metal, e.g., Ni.

DETAILED DESCRIPTION

Hereinafter, a few embodiments of the present invention will bedescribed with reference to the accompanying drawings. In the followingdescription, the same elements will be designated by the same referencenumerals although they are shown in different drawings. Further, in thefollowing description of the present disclosure, a detailed descriptionof known functions and configurations incorporated herein will beomitted when it may make the subject matter of the present inventionrather unclear.

In addition, terms, such as first, second, A, B, (a), (b) or the likemay be used herein when describing components of the present disclosure.These terms are merely used to distinguish one structural element fromother structural elements, and a property, an order, a sequence and thelike of a corresponding structural element are not limited by the term.It should be noted that if it is described in the specification that onecomponent is “connected,” “coupled” or “joined” to another component, athird component may be “connected,” “coupled,” and “joined” between thefirst and second components, although the first component may bedirectly connected, coupled or joined to the second component. Likewise,when it is described that a certain element is formed “on” or “under”another element, it should be understood that the certain element may beformed either directly or indirectly via a still another element on orunder another element.

FIG. 1 is a view illustrating a system configuration of an organic lightemitting display device to which exemplary embodiments may be applied.

Referring to FIG. 1, the organic light emitting display device 100 mayinclude a timing controller 110, a data driving unit 120, a gate drivingunit 130, a display panel 140, and a graphics controller 150.

Referring to FIG. 1, a pixel P is defined at each region on a firstsubstrate, at which data lines DL1, DL2, . . . , DLn extending in onedirection cross with gate lines GL1, GL2, . . . , GLn extending in aperpendicular direction.

Each pixel P on the display panel 140 may include at least one organiclight emitting device including an anode as a first electrode, a cathodeas a second electrode, and an organic light emitting layer. Each organiclight emitting device in the pixel P may include at least one organiclight emitting layer among red, green, blue, and white light organicemitting layers, or a white light organic emitting layer.

Each pixel P has a gate line GLy, a data line DLx, and a high voltageline VDDx (not shown) for supplying a high voltage. Further, in eachpixel P, a switching transistor is interposed between the gate line GLyand the data line DLx, and a driving transistor is formed between asource electrode (or a drain electrode) of the switching transistor andthe organic light emitting diode including the anode, the cathode andthe organic light emitting layer and the high voltage line VDD.

The driving transistor is an oxide thin film transistor, and may includean oxide layer consisting of Indium Gallium Zinc Oxide (IGZO), Zinc TinOxide (ZTO), Zinc Indium Oxide (ZIO), a gate electrode, a source/drainelectrode, and the like.

A passivation layer may be formed on the organic light emitting diode,which protects the organic light emitting diode from moisture andoxygen. Also, an adhesive layer may be formed on the passivation layer.A second substrate may be formed on the adhesive layer.

The second substrate may be made of a metal foil or a metal foil alloyand includes a hydrogen capturing metal. In addition, the firstsubstrate may be made of a metal foil or a metal foil alloy and includea hydrogen capturing metal, according to a light emitting direction ofthe organic light emitting device.

Further, a hydrogen capturing layer made of a metal foil or a metal foilalloy including a hydrogen capturing metal may be formed on an innersurface of at least one of the first substrate or the second substrate,or may be formed on both substrates.

Hereinafter, the organic light emitting device constituting pixels onthe above-mentioned organic light emitting display device will bedescribed in detail with reference to the accompanying drawings.

FIG. 2 is a sectional view schematically illustrating an organic lightemitting device according to a first exemplary embodiment.

Referring to FIG. 2, an organic light emitting device 200 according tothis embodiment includes an oxide thin film transistor 220 arranged onthe first substrate 210 in which a pixel region is defined, an organiclight emitting diode 230 formed on the oxide thin film transistor 220, apassivation layer 240 formed on the organic light emitting diode 230, anadhesive layer 250 formed on the passivation layer 240, and a secondsubstrate 260 formed on the adhesive layer 250.

Light emission of the organic light emitting device 200 is classifiedinto a top emission in which a light is emitted to the second substrate260 by reference from the oxide thin film transistor 220 and a bottomemission in which the light is emitted to the first substrate 210 byreference from the oxide thin film transistor 220.

In the organic light emitting device 200 according to one aspect, in thecase of the bottom emission, the first substrate 210 and the firstelectrode, which is a pixel electrode, should be made of a transparentmaterial including a semi-transparent material, while in the case of thetop emission, the passivation layer 240, the adhesive layer 250, and thesecond substrate 260 should be made of the transparent materialincluding the semi-transparent material.

Although the organic light emitting device 200 according the embodimentswill be described as an example of the bottom emission, the presentinvention is not limited thereto and may be a top emission.

The oxide thin film transistor 220 requires a high driving voltagecompared with a poly-silicon transistor, but has an advantage of a lowfabrication cost because of a small number of processes. Further, theoxide thin film transistor 220 has an excellent off currentcharacteristic and may be driven by a low frequency equal to or lowerthan about 60 Hz.

The oxide thin film transistor 220 according to the followingembodiments will be described as an example of a bottom gate type inwhich a gate electrode is formed on a lower portion of a source/drainelectrode. However, the present invention is not limited thereto, andmay be a top gate type in which the gate electrode is formed on an upperportion of the source/drain electrode.

An organic light emitting diode 230 may be formed on the oxide thin filmtransistor 220. The organic light emitting diode 230 may include twoelectrodes and an organic layer. In this case, the organic layerincludes an organic light emitting layer, and further includes a holeinjection layer, a hole transfer layer, an electron transfer layer, anelectron injection layer, and the like for smooth formation of anexciton.

Next, a film type passivation layer 240 is formed on the organic lightemitting diode 230, and may be made in the form of an inorganic filmcontaining hydrogen generated during the formation thereof.

A hybrid encapsulation structure may be in a form in which an adhesivelayer 250 is formed on the passivation layer 240, and a second substrate260 is formed on the adhesive layer 250.

Because the above-mentioned oxide thin film transistor 220 includes anoxide, a threshold voltage shift may occur due to a change of the oxideproperties. Therefore, in order to prevent the threshold voltage shiftdue to residual hydrogen in the organic light emitting device 200, atleast one of the first and second substrates 210 and 260 may be formedof a metal foil or a metal foil alloy and include a hydrogen capturingmetal. As another example, at least one of the first and secondsubstrates 210 and 260 may include a hydrogen capturing layer formed ofmetal foil or metal foil alloy which includes a hydrogen capturingmetal. FIGS. 10 to 12 show a structure of the organic light emittingdevice having a separate hydrogen capturing layer coated thereon, andthe structure of the organic light emitting device will be described indetail with reference to the corresponding drawings.

The metal foil refers to a metal with malleability and ductility forformation of foil. The metal foil may be made from a relativelyplentiful metal, but is not limited thereto. Since the organic lightemitting device 200 according to one embodiment is fabricated by usingrelatively plentiful metal, there is an advantage in reducing afabricating cost of the organic light emitting display device.

The metal foil alloy may be formed by alloying the above-mentioned metalfoil with another metallic material, and may include a hydrogencapturing metal capable of capturing residual hydrogen throughinterstices of a lattice of a face centered cubic lattice structure or abody centered cubic lattice structure.

Further, the hydrogen capturing metal may be a hydrogen resolving metalcapable of dissociating the residual hydrogen in a state from moleculesto atoms, but is not limited thereto. In other words, the hydrogencapturing metals are metals with high performance, capable ofdissociating a hydrogen molecule into hydrogen atoms so as to forminterstitial solid solution or metal hydride.

The metal foil or the metal foil alloy may be a face centered cubiclattice structure or a body centered cubic lattice structure which hasinterstices of lattice capturing residual hydrogen generated in formingthe organic light emitting device 200. The metal foil or the metal foilalloy with the face centered cubic lattice structure or the bodycentered cubic lattice structure may form the interstitial solidsolution or the metal hydride along with residual hydrogen generated informing the organic light emitting device 200.

The second substrate 260 may have the same thermal expansion coefficientas that of the first substrate 210 to prevent the device 200 frombending when a process is performed at a high temperature.

Hereinafter, the organic light emitting device having the secondsubstrate 260 formed of the metal foil or the metal foil alloy and themethod of manufacturing the same will be described with reference toFIGS. 3 to 9D.

FIG. 3 is a sectional view of an organic light emitting device accordingto a second exemplary embodiment.

Referring to FIG. 3, an organic light emitting device 300 according to asecond embodiment includes an oxide thin film transistor 320 arranged onthe first substrate 310 in which a pixel region is defined, an organiclight emitting diode 330 formed on the oxide thin film transistor 320, apassivation layer 340 formed on the organic light emitting diode 330, anadhesive layer 350 formed on the passivation layer 340, and a secondsubstrate 360 formed on the adhesive layer 350.

The oxide thin film transistor 320 is formed on the first substrate 310.The oxide thin film transistor 320 includes a gate electrode 321, a gateinsulation layer 323 formed on the gate electrode 321 to cover the firstsubstrate 310, an active layer 325 formed of an oxide on the gateinsulation layer 323, a source/drain electrode 327 formed on the activelayer 325 and connected to the first electrode 331, and an etch stopper326 formed between the source electrode and the drain electrode 327 onthe active layer 325.

The first substrate 310 may be a plastic substrate includingpolyethylene terephthalate (PET), polyethylene naphthalate (PEN), andpolyimide or a glass substrate. Further, the first substrate 310 mayfurther include a buffer layer for isolating penetration of impureelements, which is formed thereon. The buffer layer may be formed of,for example, a monolayer or multiple layers of silicon nitride orsilicon oxide.

The gate electrode 321 formed on the first substrate 310 may be formedwith a monolayer or multiple layers of at least one metal or alloy ofAl, Pt, Pd, Ag, Mg, Au, Ni, Nd, Ir, Cr, Li, Ca, Mo, Ti, W, and Cu.

An insulation film 323 may be formed on the first substrate 310 on whichthe gate electrode 321 is formed. The gate insulation film 323 may beformed of an inorganic insulation material such as SiO_(x), SiN_(x),SiON, Al₂O₃, TiO₂, Ta₂O₅, HfO₂, ZrO₂, BST, and PZT, an organicinsulation material including benzocyclobutene (BCB) and acryl-basedresin, or a combination thereof.

The active layer 325 may be formed of an oxide on the gate insulation323. The active layer 325 may be an oxide, for example, at least onezinc oxide based oxide of indium gallium zinc oxide (IGZO), zinc tinoxide (ZTO) and zinc indium oxide (ZIO), but is not limited thereto.

The source/drain electrode 327 on the active layer 325 and electricallyconnected to the first electrode 331 may be formed with a mono layer ormultiple layers of at least one metal or alloy of Al, Pt, Pd, Ag, Mg,Au, Ni, Nd, Ir, Cr, Li, Ca, Mo, Ti, W, and Cu. Especially, thesource/drain electrode 327 may be formed of a metal with a high meltingpoint, such as chrome (Cr) or tantalum (Ta), but is not limited thereto.

The etch stopper 326 may be formed between the source/drain electrodes327 on the active layer 325, which prevents the active layer 325 frombeing etched by an etching solution when a patterning process isperformed on the oxide thin film transistor 320 by photolithography.However, the etch stopper 326 may be omitted according to the etchingsolution.

A planarization layer 329 may be formed on the source/drain electrode327 to cover the source/drain electrodes 327 and the gate insulationfilm 323. The planarization layer 329 may be formed of, for example, atleast one of silicon oxynitride (SiON), silicon nitride (SiNx), siliconoxide (SiOx), and aluminum oxide (AlOx) as a hydrogen containinginorganic film with a hydrophobic characteristic, sufficient mechanicalstrength, water vapor resistance, and trouble-free film formation.

The organic light emitting diode 330 may be formed on the planarizationlayer 329, which may include a first electrode 331, a bank 333, anorganic layer 335, and a second electrode 337.

The first electrode 331 may be electrically connected to thesource/drain electrode 37 through a via hole 328 formed in theplanarization layer 329.

The first electrode 331 may be formed of a transparent conductivematerial having a relatively large work function and playing a role ofan anode electrode (positive electrode). For example, a metal oxide suchas indium tin oxide (ITO) or indium zinc oxide (IZO), a mixture of ametal and an oxide such as ZnO: Al or SnO2: Sb, and conductive polymersuch as poly (3-methyl-thiophene), poly [3,4-(ethylene-1,2-dioxy)thiophene] (PEDT), polypyrrole, polyaniline, etc., may be used as thetransparent conductive material. Further, the first electrode 331 may bea carbon nanotube, graphene, a silver nanowire, and the like.

In the case of the top emission, a reflection plate made of a metalmaterial with excellent reflection efficiency, for example, aluminum(Al) or silver (Ag), may be further formed as an auxiliary electrode onupper and lower portions of the first electrode 331 in order to improvethe reflection efficiency.

The bank 333 may be formed on an edge portion of the first electrode331, in which an opening is formed, so that the first electrode 331 isexposed. The bank 333 may be formed of an inorganic insulation materialsuch as silicon nitride (SiNx) and silicon oxide (SiOx), an organicinsulation material such as benzocyclobutene or acrylic resin, or acombination thereof, but is not limited thereto.

An organic layer 335 may be formed on the first electrode 331 which isexposed, on which a hole injection layer (HIL), a hole transfer layer(HTL), an emitting layer (EL), an electron transfer layer (ETL), anelectron injection layer (EIL), and the like may be sequentiallylaminated so that a hole and an electron are smoothly transferred toform an exciton.

A second electrode 337, which is a cathode electrode, may be formed onthe organic layer 335. In the case of the bottom emission, for example,the second electrode 337 may be formed of a metal with a monolayer ormultiple layers of an alloy in which a first metal, e.g., silver (Ag),and a second metal, e.g., magnesium, are mixed in a desired proportion.

The passivation layer 340 may be formed on the organic light emittingdiode 330 to cover an entire upper surface of the second electrode 337.

The passivation layer 340 may be formed of, for example, at least one ofsilicon oxy-nitride (SiON), silicon nitride (SiNx), silicon oxide(SiOx), and aluminum oxide (AlOx) as a hydrogen containing inorganicfilm with a hydrophobic characteristic, sufficient mechanical strength,water vapor resistance, and trouble-free film formation.

A film type passivation layer 340 postpones permeation of moisture oroxygen, to prevent the organic layer 335, which is sensitive to moistureor oxygen, from absorbing the moisture.

The passivation layer 340 also functions as a protection layer, and mayfurther include a bit having at least one metal of Ba, Ca, Cu, Fe, Hf,La, Mg, Nb, Pd, Pt, Se, Sr, Ta, Ti, V, and Zr and prevent residualhydrogen in the device from being diffused into the oxide thin filmtransistor 320.

The passivation layer 340 may be formed of a monolayer having athickness of about 0.5 μm to about 1.0 μm, or multiple layers without alimitation thereto.

The planarization layer 329 or the passivation layer 340 may be formedin processes of a chemical vapor deposition, a physical vapordeposition, a plasma vapor deposition, and the like. Particularly, whenthe planarization layer 329 or the passivation layer 340 is formed inthe chemical vapor deposition process, hydrogen is not withdrawn andremains in the organic light emitting device 300. A problem in ofresidual hydrogen generated in the panel will be described later.

Further, the adhesive layer 350 may be formed on the passivation layer340, which may be formed of a transparent adhesive material with anexcellent optical transmission, for example, an adhesive film or opticalcleared adhesive (OCA). The adhesive layer may be formed in a manner ofa metal lid, a frit sealing, a thin film deposition, or another suitableprocess.

The adhesive layer 350 may have a face sealing structure of adhering ona face of the second substrate 360, but is not limited thereto. Theadhesive layer 350 protects the organic light emitting diode 330 fromexternal contamination such as moisture, and also flattens the secondsubstrate 360 encapsulating the organic light emitting diode 330.

Further, the adhesive layer 350 functions as a protection layer, and mayfurther include a bit of at least one metal of Ba, Ca, Cu, Fe, Hf, La,Mg, Nb, Pd, Pt, Se, Sr, Ta, Ti, V, and Zr and prevent residual hydrogenin the device from being diffused into the oxide thin film transistor320.

The second substrate 360 may be formed on the adhesive layer 350. Thesecond substrate 360 may be formed of a metal foil with malleability andductility for formation of foil. Especially, the metal foil may includea relatively available element, for example, Fe, Cu, Al, and the like asdescribed above, with advantages of a competitive material andmanufacturing costs.

In addition, the second substrate 360 may be formed by alloying metalfoil with another metallic material, and may include a hydrogencapturing metal capable of capturing residual hydrogen through theinterstices in the lattice of the face centered cubic lattice structureor the body centered cubic lattice structure. The hydrogen capturingmetal may be at least one of Ba, Ca, Cu, Fe, Hf, La, Mg, Nb, Ni, Pd, Pt,Se, Sr, Ta, Ti, V, and Zr. Particularly, the second substrate 360 may bea metal foil alloy including one or more hydrogen capturing metals basedon the above-mentioned metal foil.

The hydrogen capturing metal may be a hydrogen resolving metal capableof dissociating and capturing the residual hydrogen molecule throughphysical and chemical absorption. The hydrogen resolving metal may be ametal catalyst used as a catalyst in a hydrogen resolving reaction.

The second substrate 360 formed of the metal foil or the metal foilalloy including the hydrogen capturing metal based on the metal foil mayhave the same thermal expansion coefficient as that of the firstsubstrate 310. If both substrates 310 and 360 have different thermalexpansion coefficients, the device may bend when the process isperformed in a high temperature condition. If the organic light emittingdevice 300 is bent, light modulation may be impossible resulting inimage distortion.

Therefore, in the case that the second substrate 360 is formed of themetal foil alloy, a composition ratio of the metal foil alloy must bedesigned so that the second substrate 360 has the same thermal expansioncoefficient as that of the first substrate 310. For example, if thefirst substrate 310 is the glass substrate and has the thermal expansioncoefficient of 2.5 ppm/° C.˜5.5 ppm/° C., the second substrate 360 maybe a metal foil alloy of iron and nickel in which a composition ratio ofnickel added to iron is about 33%˜42%.

Since the metal foil or the metal foil alloy has the body centered cubiclattice structure or the face centered cubic lattice structure andresidual hydrogen expands or is absorbed between metal lattices, it ispossible to prevent expansion of the residual hydrogen toward the oxidethin film transistor 320.

FIG. 4A is a perspective view illustrating a body centered cubic latticestructure of a single metal foil constituting the second substrate, andFIG. 4B is a perspective view illustrating a face centered cubic latticestructure of the single metal foil constituting the second substrate.Further, FIG. 5A is a perspective view illustrating a body centeredcubic lattice structure of a metal foil alloy constituting the secondsubstrate, and FIG. 5B is a perspective view illustrating a facecentered cubic lattice structure of the metal foil alloy constitutingthe second substrate.

Referring to FIG. 4A, the body centered cubic lattice structure of themetal foil constituting the second substrate 360 is a unit crystallattice in which eight atoms 420 a are arranged at eight corners of thecubic lattice 410 a respectively, and one atom 420 a is present at thecenter of the lattice 410 a. The number of atoms in the unit lattice istwo. The metal foil of the body centered lattice structure may be Li,Na, Cr, α-Fe, Mo, W, K, etc.

Referring to FIG. 5A, in the case of the body centered cubic latticestructure of the metal foil alloy constituting the second substrate 360,the first metal 520 a is located at four corners and a center of thelattice 510 a, and the second metal 521 a is located at four remainingcorners of the lattice. Here, the first metal may be the metal foilhaving the body centered cubic lattice structure, and the second metalmay be the hydrogen capturing metal. However, the first metal and thesecond metal are not limited thereto. Further, a relative position ofthe first metal 520 a and the second metal 521 a may be varied accordingto the composition ratio or a forming condition thereof.

In addition, a packing factor of the metal foil or the metal foil alloyconstituting the second substrate 360 having the body centered cubiclattice structure may be, for example, about 68%.

Referring to FIG. 4B, in the face centered cubic lattice structure ofthe metal foil constituting the second substrate 360, an atom 420 b isarranged at each corner and in the center of each face of the lattice410 b, and the number of atoms in a unit lattice is four. The metal foilof the face centered cubic lattice structure may be Pt, Pb, Ni, γ-Fe,Cu, Al, Au, Ag, etc.

Referring to FIG. 5B, in the face centered cubic lattice structure ofthe metal foil alloy constituting the second substrate 360, the firstmetal 520 a is arranged at the center and four corners of the lattice510 b and the centers of four faces, and the second metal 521 b isarranged at four corners and two faces. Herein, the first metal may bethe metal foil having the face centered cubic lattice structure, and thesecond metal may be the hydrogen capturing metal. However, the firstmetal and the second metal are not limited thereto. Further, a relativeposition of the first metal 520 a and the second metal 521 a may bevaried according to the composition ratio or a condition of forming themetals.

Furthermore, a packing factor of the single metal foil or the metal foilalloy having the face centered cubic lattice structure is, for example,about 74%.

Accordingly, when the second substrate 360 is formed of the metal foilor the metal foil alloy having the body centered cubic latticestructure, pores of about 32% are formed. If the second substrate 360 isformed of the metal foil or the metal foil alloy having the facecentered cubic lattice structure, pores of about 26% are formed.Therefore, residual hydrogen generated in the process of depositing thepassivation layer 340 or the planarization layer 329 may be diffused inthe second substrate 360, and solidified in the metal foil so as to formthe solid solution or the metal hydride, thereby storing the residualhydrogen in the organic light emitting device 300.

FIGS. 6A to 6D are sectional views illustrating a mechanism in whichresidual hydrogen generated during a device process is captured in ametal foil or a metal foil alloy having a lattice structure.

Referring to FIGS. 3, 4A, 4B, 5A, 5B and 6A-6D, the residual hydrogen630 deoxidizes an oxide on the active layer 325 of the oxide thin filmtransistor 320, so as to change characteristics of the device.

That is, gas is decomposed in various forms and remains in the devicewhen it is in a plasma state. For example, in a deposition process, suchas plasma enhanced chemical vapor deposition (PECVD), using plasma ofsilicon hydride (SiH₄) and amine (NH₃) gas, diffusible hydrogen that caneasily move within a solid in a monoatomic or ion state at a relativelylow temperature and non-diffusible hydrogen bonded to another atom maygenerate a molecule.

In the case of a general organic light emitting device 300, when theresidual hydrogen is present, it can freely move within the solid.Especially, in the case of using a typical glass substrate, the residualhydrogen 630 may be confined between both glass substrates. If thisoccurs, some hydrogen may approach and degrade the active layer 325 ofthe oxide thin film transistor 320.

Especially, if silicon nitride (SiNx), silicon oxynitride (SiON), or thelike is formed as the planarization layer 329 or the passivation layer340 by the plasma enhanced chemical vapor deposition (PECVD), a largeamount of hydrogen and impurities are generated. In the case of theorganic light emitting device 300, since a processing temperature islimited within 100° C. to minimize thermal damage to the organic lightemitting diode 330, the amount of the residual hydrogen 630 increases.

With reference to chemical formula (1), when the silicon nitride isdeposited by using a mixed gas of SiH₄ and NH₃ in the process of theplasma chemical vapor deposition, so as to form the passivation layer340, the residual hydrogen (H2) 630 of about 15-40% is generated.SiH₄+2NH₃→SiN₂+5H₂  (1)

FIG. 7A is a sectional view illustrating a general organic lightemitting device in which the residual hydrogen is diffused into theoxide thin film transistor so as to shift a threshold voltage of theoxide thin film transistor. FIG. 7B is a sectional view illustrating anorganic light emitting device according to the second embodiment of FIG.3, in which the residual hydrogen is diffused into the second substrate.

Referring to FIG. 7A, the second substrate 360 is a glass substrate, andthe residual hydrogen 630 generated in the deposition process includesnon-diffusible hydrogen 710 in a molecule and diffusible hydrogen 720dissociated in an atomic state. The diffusible hydrogen 720, which isgenerated in the deposition process of the passivation layer 340 and theadhesive layer 350 and remains within the device, is not captured in thefirst substrate 310 or the second substrate 360, especially, the secondsubstrate 360. Therefore, the diffusible hydrogen 720 may be freelydiffused between the first substrate 310 and the second substrate 360.Thus, some of the diffusible hydrogen 720 is diffused within the oxidethin film transistor 320, so as to deoxidize the oxide constituting theactive layer 325 of the oxide thin film transistor 320.

The deoxidization of the active layer 325 causes a change in an electricbehavior of the oxide thin film transistor 320, resulting in a thresholdvoltage shift. If the extent of the threshold voltage shift is deviatedfrom a range of a compensation for a circuit of an organic lightemitting display panel, the threshold voltage shift can result in astain or a deviation of luminance on the screen.

Referring to FIG. 7B, in the organic light emitting device 300 accordingto the second embodiment in which the second substrate 360 is formed ofthe metal foil or the metal foil alloy, when the diffusible hydrogen 720present in a lamination structure such as the planarization layer 329 orthe passivation layer 340 is diffused through the adhesive layer 350 andapproaches the surface of the second substrate 360, the diffusiblehydrogen 720 is captured within the second substrate 360, so as to formthe interstitial solid solution or the metal hydride. Thereby, it ispossible to prevent the deoxidization of the oxide thin film transistor320.

For example, a diffusion rate of the residual hydrogen 630 within iron(Fe) which is one of components for the metal foil is, for example,1×10⁻⁴ cm²/sec at the normal temperature and is faster, compared with adiffusion rate of hydrogen within carbon or nitrogen, for example,1×10⁻¹⁶ cm²/sec. The diffusion rate of the hydrogen is faster within apolymer material because of a presence of more free volume due to astructure of the polymer. It can be noted that the diffusion rate of thehydrogen within the polymer material is faster than a diffusion rate ofhydrogen within a general polymer material, e.g., 1×10⁻⁴ cm²/sec.Accordingly, since the diffusion rate of the residual hydrogen 630within the second substrate 360 is relatively faster than that withinthe adhesive layer 350 formed of the polymer material, the residualhydrogen 630 may be diffused into interstices 620 of the lattice of themetal foil or the metal foil alloy (illustrated in FIG. 6) constitutingthe second substrate 360.

With reference to chemical formula (2), the metal foil or the metal foilalloy 610 constituting the second substrate 360 may chemically reactwith hydrogen molecules or hydrogen atoms diffused and approaching thesurface of the second substrate 360, so as to form the metal hydride.2Me+xH₂→2MeH_(x)  (2)

(Me: the metal foil or metal foil alloy)

For example, hydrogen capturing metals included in the metal foil alloy,for example, Ca, Nb, Pd, Se, Sr, Ta, Ti (especially, β-Ti), and V amongBa, Ca, Cu, Fe, Hf, La, Mg, Nb, Ni, Pd, Pt, Se, Sr, Ta, Ti, V, and Zrform the metal hydride along with the residual hydrogen.

The non-diffusible hydrogen 710 may form an interstitial solid solutionin the second substrate 360 made of the metal foil or the metal foilalloy through physical and chemical absorption. For example, in the caseof the metal foil alloy such as Fe—Ti, La—Ti, Mg—Ni, etc., although thehydrogen is not diffusible hydrogen but a hydrogen molecule, when thehydrogen is physically absorbed on the surface of the metal foil or themetal foil alloy 610 by Van Der Waals attraction (see FIG. 6B andchemical formula (3)), the hydrogen is chemically absorbed through aprocess of dissociating the hydrogen to hydrogen atoms (see FIG. 6(C)and chemical formula (4), below) and is diffused into the interstice 620in the body centered cubic lattice structure or the face centered cubiclattice structure, so as to be the interstitial solid solution (see FIG.6(D)).2Me+H₂→2MeH_(ads)  (3)MeH_(ads)→MeH_(abs)  (4)

According to the above-mentioned principle, the residual hydrogen 630within the organic light emitting device 300 is effectively captured andstored in the second substrate 360 formed of the metal foil or the metalfoil alloy, thereby preventing a functional degradation of the oxidethin film transistor 320 due to the residual hydrogen 630.

Briefly, in the case that the second substrate 360 is formed of themetal foil or the metal foil alloy, the residual hydrogen 630 in theorganic light emitting device 300 is effectively diffused and captured,so as to prevent the deoxidization of the oxide of the above-mentionedoxide thin film transistor 320. Thereby, it is possible to prevent aninferior organic light emitting device 300 and to produce the organiclight emitting device 300 with a low cost and high efficiency. Further,since instability restricted in the oxide thin film transistor 320 canbe reduced, applications may increase.

Up to now, the organic light emitting device 300 according to the secondembodiment has been described. Hereinafter, a process of fabricating anorganic light emitting device according to this embodiment will bedescribed.

FIG. 8 is a flowchart illustrating a process of fabricating an organiclight emitting device according to the second exemplary embodiment.

Referring to FIGS. 3 and 8, the process 800 of fabricating the organiclight emitting device according to the second embodiment includespreparing a first substrate 310 in which a pixel region is defined instep S810, forming an oxide thin film transistor 320 on the firstsubstrate 310 in step S820, forming an organic light emitting diode 330on the oxide thin film transistor in correspondence to the pixel regionof the first substrate 310 in step S830, forming a passivation layer 340on the organic light emitting diode 330 in step S840, forming anadhesive layer 350 on the passivation layer 340 in step S850, andforming a second substrate 360 made of a metal foil or a metal foilalloy including a hydrogen capturing metal in step S860.

First, the first substrate 310 in which the pixel region is defined isprepared in step S810. In step S810, the preparing of the firstsubstrate 310 may include cleaning a surface of the first substrate 310with a plasma treatment in order to improve the surface of the firstsubstrate 310.

Then, the oxide thin film transistor 320 is formed on the firstsubstrate 310 in step S820. In step S820, the oxide thin film transistor320 including the oxide may be formed on the first substrate 310 inwhich the pixel is defined.

In step S820, a gate electrode 321 may be formed in a photolithographymanner, and a gate insulation film 323 is deposited on the substrate 310to cover the gate electrode 321. Then, the active layer 325 is depositedon the gate insulation film 323. An etch stopper 326 may be formed onthe active layer 325 in order to prevent the metal oxide from beinginfluenced, but may be omitted according to the etching solution. If theetching solution does not attack the metal oxide the etch stopper wouldnot be necessary.

Continuing, a source/drain electrode 327 is formed in aphotolithographic manner to have a double step, and a planarizationlayer 329 is formed on the gate insulation film 323 to cover an exposedportion of the source/drain electrode 327 and the active layer 325.Then, the planarization layer 329 is patterned to form a via hole 328exposing the source/drain electrode 327.

The planarization layer 329 may be a hydrogen containing inorganic filmsuch as silicon oxynitride (SiON), silicon nitride (SiNx), silicon oxide(SiOx), and aluminum oxide (AlOx). The planarization layer 329 may beformed by a process of a chemical vapor deposition, a physical vapordeposition, a plasma vapor deposition, and the like.

In this embodiment, although the oxide thin film transistor 320 havingthe bottom gate has been described, the oxide thin film transistor 320may be fabricated in a top gate manner.

Next, the organic light emitting diode 330 is formed on the oxide thinfilm transistor 320 in step S830. The organic light emitting diodeincludes a first electrode 331 electrically contacting the source/drainelectrode 327 of the oxide thin film transistor 320 through the via hole328, an organic layer 335 including an organic light emitting layerformed on the first electrode, and a second electrode 337 formed on theorganic layer 335. For smooth formation of an exciton, the organic layer335 may include a hole injection layer, a hole transfer layer, anorganic light emitting layer, an electron transfer layer, an electroninjection layer, and the like.

In step S830, a bank 333 made of an inorganic insulation material, anorganic material or a combination thereof is formed on the firstelectrode in a non-light emitting region in order to define a lightemitting region.

The organic layer 335 may be formed in processes of a chemical vapordeposition, a physical vapor deposition, a solution process, and thelike. For example, the organic light emitting layer may be formed in amanner of depositing an RGB light emitting material using a fine metalmask (FMM) or using laser induced thermal imaging (LITI). Further, aftera white light emitting material is deposited on a whole surface, a colorfilter may be used in a next process.

In turn, a second electrode 337 is formed on an organic layer 335through a thermal evaporation, an ion beam deposition, or other suitableprocess.

Next, the passivation layer 340 is formed on the organic light emittingdiode 330 in step S840. In step S840, the passivation layer 340 may beformed in processes of the chemical vapor deposition, the physical vapordeposition, the plasma chemical vapor deposition, and the like. Thepassivation layer 340 may be formed of a hydrogen containing inorganicfilm which contains hydrogen generated in the process.

Next, the adhesive layer 350 is formed on the passivation layer 340 instep S850. The adhesive 350 may be formed of a transparent adhesivematerial with an excellent light transmission.

The second substrate 360 is formed on the adhesive layer 350 in stepS860.

In this step S860, the second substrate 360 may be made of a metal foilor a metal foil alloy and includes a hydrogen capturing metal. Thesecond substrate 360 may include a hydrogen capturing layer formed of ametal foil or a metal foil alloy including a hydrogen capturing metalbased on the metal foil, on an inner surface thereof.

In the step S850 of forming the adhesive layer and the step S860 offorming the second substrate, the adhesive layer and the secondsubstrate may have a face encapsulation structure.

FIGS. 9A to 9D are sectional views illustrating an organic lightemitting device in a sequence of processes of fabricating the organiclight device according to the second embodiment.

Referring to FIG. 9A first, after the first substrate 310 is preparedand cleaned, the oxide thin film transistor 320 is formed. In cleansingthe first substrate 310, a plasma treatment may be performed to improvethe surface.

A material with excellent mechanical strength or dimensional stabilitymay be selected as a material for forming the first substrate 310. Theorganic light emitting device 300 according to one embodiment is abottom emission type, and the first substrate 310 may be a plasticsubstrate including polyethylene terephthalate (PET), polyethylenenaphthalate (PEN), and polyimide or a glass substrate.

The first substrate 310 may further include a buffer layer for isolatingpenetration of an impure element, which may be formed thereon. Thebuffer layer may be formed of, for example, a monolayer or multiplelayers of silicon nitride or silicon oxide.

The oxide thin film transistor 320 is formed on the first substrate 310.

In the bottom emission type of the oxide thin film transistor 320, agate electrode 321 made of a conductive metal having a small electricresistance and a tensile stress such as aluminum, copper, and the likeis formed on the first substrate 310 formed of an insulation material.

The gate electrode 321 may be formed of a monolayer or multiple layersof at least one metal or alloy of Al, Pt, Pd, Ag, Mg, Au, Ni, Nd, Ir,Cr, Li, Ca, Mo, Ti, W, and Cu.

The gate insulation film 323 may be formed of an inorganic insulationmaterial such as SiO_(x), SiN_(x), SiON, Al₂O₃, TiO₂, Ta₂O₅, HfO₂, ZrO₂,BST, and PZT, an organic insulation material including benzocyclobutene(BCB) and acryl-based resin, or a combination thereof. An active layer325 made of a zinc oxide based oxide such as IGZO, zinc tin oxide (ZTO),zinc indium oxide (ZIO), and the like is formed on the gate insulationlayer 323, so that the gate electrode 321 is placed at a center of theactive layer 325.

The source/drain electrode 327 is formed on the active layer 325 by amono layer or multiple layers of at least one metal or alloy of Al, Pt,Pd, Ag, Mg, Au, Ni, Nd, Ir, Cr, Li, Ca, Mo, Ti, W, and Cu. Especially,the source/drain electrode 327 may be formed of a metal with a highmelting point, such as chrome (Cr) or tantalum (Ta), but is not limitedthereto.

In the process of forming the oxide thin film transistor 320, after theconductive metal such as aluminum, copper, and the like is deposited inthe chemical vapor deposition or the physical vapor deposition such assputtering, the conductive metal may be patterned by photolithography soas to form the gate electrode 321.

Then, silicon oxide or silicon nitride is deposited in the chemicalvapor deposition to cover the gate electrode, to form the gateinsulation film 323.

Indium gallium zinc oxide (IGZO), zinc tin oxide (ZTO), or zinc indiumoxide (ZIO), and the like, in which impurities are not doped, aresequentially deposited, thereby forming the active layer 325.

Continuing, the source/drain electrode 327 may be formed to have adouble step by depositing a metal such as chrome, tantalum, or the likein a deposition process including the chemical vapor deposition and in aphotolithographic manner.

Next, a hydrogen containing inorganic film, for example, silicon oxideor silicon nitride, is deposited on the gate insulation film 323 tocover an exposed portion of the source/drain electrode 327 and theactive layer 35, thereby forming the planarization layer 329. In thiscase, since the source/drain electrode 327 has the double step, it ispossible to degrade step coverage of the planarization layer 329.

Then, the planarization layer 329 is patterned to form a via hole 328exposing the drain electrode 327.

Referring to FIG. 9B, an organic light emitting diode 330 including afirst electrode, an organic layer, and a second electrode is formed.

First, the first electrode 331 is formed on the planarization layer 329.The first electrode 331 is formed in each pixel region, which iselectrically connected to the drain electrode 327 through the via hole38 and may be patterned by using a transparent material. After aphotoresist is coated, the photoresist is patterned through aphotolithographic process in which the photoresist is removed awaythrough processes of pre-baking, exposure, development, post-baking, andetching. The first electrode 331 may be an anode generating a hole.

Then, a bank 333 is formed at an edge portion of the first electrode 331and has an opening to expose a part of the first electrode 331. The bank333 has an unsmooth surface on which various wires and transistors arearranged, and is used to prevent the organic material from beingdeteriorated when an organic film is formed on the surface of the bank333 which has unevenly formed steps. That is, the bank 333 is formed ina non-light emitting region to distinguish a region in which the oxidethin film transistor 320 and various wires are formed from a lightemitting region in which thin films are merely laminated on a flatsubstrate.

An organic layer 335 is formed on the first electrode 331 and the bank333 which are exposed. More particularly, the hole injection layer(HIL), the hole transfer layer (HTL), the light emitting layer (EL), theelectron transfer layer (ETL), and the electron injection layer (HIL)are sequentially laminated. Holes and electrons combine on the lightemitting layer to form an exciton, and the exciton drops from an excitedstate to a ground state to emit light, thereby displaying an image.

The organic layer 335 may be formed by a chemical vapor deposition, aphysical vapor deposition, a solution process, and the like. Forexample, the organic light emitting layer may be formed in a manner ofdepositing an RGB light emitting material using a fine metal mask (FMM)or performing the solution process such as laser induced thermal imaging(LITI) or a coating. The LITI is a process in which a laser beam isselectively emitted on a donor film and a thin film is selectivelytransferred by radiated heat. In the case of using a white lightemitting device, a face surface is formed on the first electrode 331,and a color filter is deposited.

The second substrate 337 may be formed on the organic layer 335. Thesecond electrode 337 may be a cathode, and may be made of a conductivematerial with a relatively small work function value. For example, thesecond electrode 337 may be formed of a metal with a monolayer ormultiple layers of alloy in which a first metal, e.g., silver (Ag), anda second metal, e.g., magnesium, are mixed in a desired proportion.

In this case, the second electrode 337 may be formed by a lowtemperature deposition in order to minimize damage of the organic layer335 due to heat or plasma, but is not limited thereto.

Referring to FIG. 9C, the passivation layer 340 may be formed on theorganic light emitting diode 330.

The passivation layer 340 plays a role of primarily protecting theorganic light emitting diode 330 from moisture and impurities. Thepassivation layer 340 may be formed of silicon oxynitride (SiON),silicon nitride (SiNx), silicon oxide (SiOx), or aluminum oxide (AlOx)through a chemical vapor deposition, a physical vapor deposition, aplasma chemical vapor deposition, and the like. In this process,residual hydrogen 630 is generated.

The passivation layer 340 is a hydrogen containing inorganic film whichis formed of, for example, silicon oxynitride (SiON), silicon nitride(SiNx), silicon oxide (SiOx), or aluminum oxide (AlOx), and containshydrogen generated in the deposition process, and is formed with amonolayer to have a thickness of about 0.5 μm to about 1.0 μm, but isnot limited thereto and may be formed with multiple layers.

As described above with reference to the chemical formula (1), thesilicon nitride may be deposited by using a mixed gas of SiH₄ and NH₃ inthe plasma chemical vapor deposition process, so as to form thepassivation layer 340.

Referring to FIG. 9D, after the passivation layer 340 is formed, theadhesive layer 350 and the second substrate 360 are combined, so thatthe organic light emitting device 300 according to another embodiment iscompleted.

An encapsulation according to one embodiment may be performed in a faceencapsulation manner. That is, a film type adhesive layer 350 may beformed on the passivation layer 340, and finally a second substrate 360made of a metal foil or a metal foil alloy is formed.

According to the embodiments of the present invention, a hybridencapsulation in which the passivation layer 340 is deposited and thesecond substrate 360 is formed is used in an adhesive manner, but anadhesive manner is not limited thereto. Accordingly, the adhesive mannermay be a metal lead or a glass lead in which the second substrate 360made of the metal foil or the metal foil alloy covers the device and isadhered by a sealant, a frit sealing manner in which a frit includingglass powder is cured to encapsulate the first substrate 210 with thesecond substrate 360 and the substrate, or an encapsulation manner usinga thin film deposition.

To form the second substrate 360 on the adhesive layer 350, first thesecond substrate 360 is prepared and impurities on the second substrate360 are removed through a UV cleaning using ultraviolet radiation, forexample. The second substrate 360 may be formed of a metal foil or ametal foil alloy including a hydrogen capturing metal capable of storingdiffusible hydrogen 720 and non-diffusible hydrogen 710 in the device.

After a cleaning step, residual gas is removed from the adhesive layer350, the adhesive layer 350 and the second substrate 360 are adhered,and then a hybrid type of the organic light emitting device 300 can becompleted.

The organic light emitting device in which the second substrate 260 ismade of the metal foil or the metal foil alloy and the method offabricating the same have been described up to now with reference toFIGS. 3 to 9D. Hereinafter, an organic light emitting device including ahydrogen capturing layer made of a metal foil or a metal foil alloy onan inner surface of a second substrate 260 and a method of fabricatingthe same will be described with reference to FIGS. 10 to 11D.

FIG. 10 is a sectional view of an organic light emitting deviceaccording to a third exemplary embodiment.

Referring to FIG. 10, an organic light emitting device 1000 according tothe third embodiment includes an oxide thin film transistor 1020arranged on the first substrate 1010 in which a pixel region is defined,an organic light emitting diode 1030 formed on the oxide thin filmtransistor 1020 and corresponding to the pixel region of the firstsubstrate 1010, a passivation layer 1040 formed on the organic lightemitting diode 1030, an adhesive layer 1050 formed on the passivationlayer 1040, and a second substrate 1060 formed on the adhesive layer1050.

Since the organic light emitting device 1000 according to the thirdembodiment has the oxide thin film transistor 1020 including the firstsubstrate 1010, a gate electrode 1021, a gate insulation layer 1023, anactive layer 1025, an etch stopper 1026 and a source/drain electrode1027, an organic light emitting diode 1030 including a first electrode1023, a bank 1033, an organic layer 1035, and a second electrode 1037, apassivation layer 1040, and an adhesive layer 1050, which aresubstantially identical to the oxide thin film transistor 320 includingthe first substrate 310, the gate electrode 321, the gate insulationfilm 323, the active layer 325, the etch stopper 326 and thesource/drain electrode 327, the organic light emitting diode 330including a first electrode 323, a bank 333, an organic layer 335 andsecond electrode 337, the passivation layer 340, and the adhesive layer350 of the organic light emitting device 300 according to the secondembodiment, the detailed description of the organic light emittingdevice 1000 will be omitted. In this case, a planarization layer 1029may be substantially identical to the planarization layer 329 of theorganic light emitting device 300 according to the second embodimentdescribed with reference to FIG. 3.

A hydrogen capturing layer 1070 made of the metal foil or the metal foilalloy is formed on an inner surface of the second substrate 1060.

In the event, the second substrate 1060 may be a glass substrate, aplastic substrate made of polyethylene terephthalate, polyethylenenaphthalate, and polyimide, and a general metal substrate, which areused for a general organic light emitting device, and a metal substratemade of a metal foil or a metal foil alloy, which is used for theorganic light emitting device 300 according to the second embodimentdescribed with reference to FIG. 3.

The hydrogen capturing layer 1070 captures and stores residual hydrogengenerated from the device in a process of depositing the planarizationlayer 1029 and the passivation layer 1050, similar to the secondsubstrate 360 made of the metal foil or the metal foil alloy describedwith reference to FIG. 3, thereby preventing the deoxidization of theactive layer 1025 of the oxide thin film transistor 1020. FIGS. 11A to11D are sectional views illustrating the organic light emitting devicein a sequence of processes of fabricating the organic light emittingdevice according to the third embodiment.

A process of fabricating the organic light emitting device according tothe third embodiment may include providing a first substrate 1010 inwhich a pixel region is defined, forming an oxide thin film transistor1020 on the first substrate 1010, forming an organic light emittingdiode 1030 on the oxide thin film transistor 1020 to correspond to thepixel region of the first substrate 1010, forming a passivation layer1040 on the organic light emitting diode 1030, forming a hydrogencapturing layer 1070 made of a metal foil or a metal foil alloyincluding a hydrogen capturing metal on a surface of the secondsubstrate 1060, forming an adhesive layer 1050 on the hydrogen capturinglayer 1070, and integrally adhering the adhesive layer 1050 to thepassivation layer 1040.

Referring to FIG. 11A, the first substrate 1010, the oxide thin filmtransistor 1020, the organic light emitting diode 1030, and thepassivation layer 1040 are sequentially formed.

Referring to FIGS. 11B and 11C, then, the adhesive layer 1050, thehydrogen capturing layer 1070, and the second substrate 1060 are formed.In other words, the hydrogen capturing layer 1070 is formed on a surfaceof the second substrate 1060, and the adhesive layer 1050 is formed onthe hydrogen capturing layer 1070.

Further, the hydrogen capturing layer 1070 may be formed on the surfaceof the second substrate 1060 by a lamination, the chemical vapordeposition, the physical vapor deposition and the like, but a method offorming the hydrogen capturing layer is not limited thereto.

Referring to FIG. 11D, the organic light emitting device 1000 iscompleted through a step of forming the adhesive layer 1050 to thepassivation layer 1040. The adhesive layer 1050 may be formed of a filmtype adhesive in a face encapsulating manner, but a manner of formingthe adhesive layer 1050 is not limited thereto.

An encapsulation structure of the organic light emitting device 1000according to another aspect may be a hybrid structure in which thepassivation layer 1040 and the second substrate 1060 are formed, but isnot limited thereto.

In addition to a method of coating the hydrogen capturing layer 1070,bits of a metal foil or a metal foil alloy may be distributed on thepassivation layer 1040 or the adhesive layer 1050, thereby removing theresidual hydrogen 630.

Further, the method of fabricating the organic light emitting deviceaccording to still another aspect has been described which includesforming the hydrogen capturing layer 1070 made of the metal foil or themetal foil alloy including a hydrogen capturing metal on a surface ofthe second substrate 1060, forming the adhesive layer 1050 on thehydrogen capturing layer 1070, and adhering the adhesive layer 1050 tothe passivation layer 1040, but the present invention is not limitedthereto. For example, the method of fabricating the organic lightemitting device according to this aspect may include forming theadhesive layer 1050 on the passivation layer 1040, and forming a secondsubstrate, which includes the hydrogen capturing layer made of the metalfoil or the metal foil alloy including the hydrogen capturing layerbased on the metal foil on an inner surface thereof, on the adhesivelayer 1050.

The organic light emitting device including the hydrogen capturing layermade of the metal foil or the metal foil alloy on an inner surface ofthe second substrate 1060 and the method of fabricating the same havebeen described up to now with reference to FIGS. 10 to 11D. Hereinafter,an organic light emitting device including a first substrate made of ametal foil or a metal foil alloy and a hydrogen capturing layer made ofthe metal foil or the metal foil alloy on an inner surface of the firstsubstrate and a method of fabricating the same will be described withreference to FIG. 12.

FIG. 12 is a sectional view schematically illustrating an organic lightemitting device according to a fourth embodiment.

Referring to FIG. 12, an organic light emitting device 1200 according tothe fourth embodiment includes an oxide thin film transistor 1230arranged on a first substrate 1210 in which a pixel region is defined,an organic light emitting diode 1240 formed on the oxide thin filmtransistor 1230, a passivation layer 1250 formed on the organic lightemitting diode 1240, an adhesive layer 1260 formed on the passivationlayer 1250, and a second substrate 1270 formed on the adhesive layer1260.

The first substrate 1210 has a hydrogen capturing layer 1220, which ismade of a metal foil or a metal foil alloy including a hydrogencapturing metal based on the metal foil, on an inner surface thereof.The hydrogen capturing layer 1220 is formed on the first substrate 1210,which is to implement a top emission type of the organic light emittingdevice 1200.

The first substrate 1210 may be a glass substrate, a plastic substratemade of polyethylene terephthalate, polyethylene naphthalate, polyimide,or the like. Alternately, the substrate 1210 may be made of metal foilor metal foil alloy for the organic light emitting device 1200 similarto the second embodiment described with reference to FIG. 3. Thehydrogen capturing layer 1220 may be coated by lamination, chemicalvapor deposition, physical vapor deposition, or the like, but thecoating manner is not limited thereto.

In the case of the top emission type organic light emitting device 1200,although it is not shown, the first substrate 1210 may be formed of ametal foil or a metal foil alloy including a hydrogen capturing metal.In this event, the hydrogen capturing layer 1220 may not be formed.

FIG. 13 is a graph illustrating a variation of hydrogen content in asecond substrate when the organic light emitting device of FIG. 3including the second substrate is made of a metal foil alloy which is ametal foil based hydrogen capturing metal, e.g., Fe, and includes ahydrogen resolving metal, e.g., Ni.

Referring to FIGS. 3 and 13, the organic light emitting device 300 shownin FIG. 3 was fabricated which include the second substrate 360 made ofthe metal foil alloy including the hydrogen resolving metal, e.g., Ni,which was a hydrogen capturing metal based on metal foil, e.g., Fe.

A content of hydrogen (C_(H)) in the second substrate 360 was 2.8 ppmbefore the second substrate 360 was adhered to the organic lightemitting device 300 (#1). However, after the adhesive layer 350 wasformed of a thermoset adhesive and is cured through a curing process ata temperature of 100° C. for three hours (#2), the content of thehydrogen (C_(H)) in the second substrate 360 increased to 5.1 ppm. Afteran acceleration test was performed at a temperature of 85° C. for onethousand hours (#3), the content of the hydrogen (C_(H)) in the secondsubstrate 360 further increased up to 5.8 ppm.

The increase of the content of the hydrogen (C_(H)) in the secondsubstrate 360 indicates that residual hydrogen 630 in the organic lightemitting device 300 was captured in the second substrate 360, and formedthe interstitial solid solution or the metal hydride.

In another aspect, the organic light emitting device shown in FIG. 3 wasfabricated except that a general glass substrate was used as the secondsubstrate 360. The passivation layer 340 had a thickness of about 0.5μm, and white bright spots were observed in several places of theorganic light emitting device when 85˜850 hours lapsed. The bright spotsoccurred when a defect was generated in the oxide thin film transistor320 as the residual hydrogen deoxidized the oxide of the active layer325 of the oxide thin film transistor 320.

As described above, in the case that the organic light emitting device300 shown in FIG. 3 was fabricated which included the second substrate360 which was the hydrogen capturing metal based on the metal foil,e.g., Fe, and included the hydrogen resolving metal, e.g., Ni, thepassivation layer 340 had a thickness of about 0.5 μm and a bright spotwas not observed in the organic light emitting device although onethousand hours lapsed when 85˜1000 hours lapsed. Similarly, in the casethat the organic light emitting device 1000 shown in FIG. 10 wasfabricated in which the hydrogen capturing layer made of the metal foilalloy which was the hydrogen capturing metal based on the metal foil,e.g., Fe, and included the hydrogen resolving metal, e.g., Ni, wasformed on the glass substrate as the second substrate, or that theorganic light emitting device 1200 shown in FIG. 12 was fabricated inwhich the hydrogen capturing metal made of the metal foil alloy whichwas the hydrogen capturing metal based on the metal foil, e.g., Fe, andincluded the hydrogen resolving metal, e.g., Ni, was formed on the glasssubstrate as the first substrate, no bright spot was observed in theorganic light emitting device although a time lapsed.

The reason for that is because defects of the oxide thin film transistorwere prevented because the hydrogen capturing layer formed on the secondsubstrate or the first substrate captured and stored the diffusiblehydrogen and the non-diffusible hydrogen.

According to the embodiments of the present invention as describedabove, in the case that the first substrate or the second substrate isformed of the metal foil or the metal foil alloy including the hydrogencapturing metal, or that the hydrogen capturing layer is coated on aninner surface of the first substrate or the second substrate, thehydrogen capturing layer effectively captures the residual hydrogengenerated in the organic light emitting device, thereby preventing theresidual hydrogen from being diffused into the light emitting layer orthe oxide thin film transistor. Further, it is possible to prevent thevariation of an electric behavior of the oxide thin film transistor andthe occurrence of the threshold voltage shift, thereby improvingreliability and quality of the organic light emitting display.

Although various embodiments have been described up to now withreference to the accompanying drawings, the present invention is notlimited to them.

In addition, since terms, such as “including,” “comprising,” and“having” mean that one or more corresponding components may exist unlessthey are specifically described to the contrary, it shall be construedthat one or more other components can be included. All the terms thatare technical, scientific or otherwise agree with the meanings asunderstood by a person skilled in the art unless defined to thecontrary. A term ordinarily used like that defined by a dictionary shallbe construed that it has a meaning equal to that in the context of arelated description, and shall not be construed in an ideal orexcessively formal meaning unless it is clearly defined in the presentspecification.

Although the embodiments of the present invention have been describedfor illustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention. Therefore, theembodiments disclosed in the present invention are intended toillustrate the scope of the technical idea of the present invention, andthe scope of the present invention is not limited by the embodiment. Thescope of the present invention shall be construed on the basis of theaccompanying claims in such a manner that all of the technical ideasincluded within the scope equivalent to the claims belong to the presentinvention.

What is claimed is:
 1. An organic light emitting device comprising: afirst substrate; an oxide thin film transistor on the first substrate; aplanarization layer on the oxide thin film transistor; an organic lightemitting diode on the planarization layer; a passivation layer on theorganic light emitting diode; and a second substrate on the passivationlayer; wherein both the first and second substrates comprise a hydrogencapturing metal capable of dissociating hydrogen molecules into hydrogenatoms, and preventing deoxidation of materials forming the oxide thinfilm transistor, and wherein the second substrate comprises a metal foilor a metal foil alloy comprising the hydrogen capturing metal.
 2. Theorganic light emitting device of claim 1, wherein the oxide thin filmtransistor includes an oxide layer selected from the group consisting ofIndium Gallium Zinc Oxide (IGZO), Zinc Tin Oxide (ZTO), and Zinc IndiumOxide (ZIO).
 3. The organic light emitting device of claim 1, wherein atleast one of the first and the second substrates includes a materialselected from the group consisting of Li, Na, Cr, α-Fe, Mo, W, and K. 4.The organic light emitting device of claim 1, wherein at least one ofthe first and the second substrates includes a material selected fromthe group consisting of Pt, Pb, Ni, γ-Fe, Cu, Al, Au, and Ag.
 5. Theorganic light emitting device of claim 1, wherein the first substratecomprises a metal foil or metal foil alloy including the hydrogencapturing metal.
 6. The organic light emitting device of claim 1,wherein the hydrogen capturing metal is capable of dissociating ahydrogen molecule into hydrogen atoms to form an interstitial solidsolution or metal hydride.
 7. The organic light emitting device of claim1, wherein the hydrogen capturing metal includes a metal foil or metalfoil alloy formed on an inner surface of one of the first and the secondsubstrates.
 8. The organic light emitting device of claim 1, furtherincluding an adhesive layer on the passivation layer, wherein theadhesive layer includes an element selected from the group consisting ofBa, Ca, Cu, Fe, Hf, La, Mg, Nb, Ni, Pd, Pt, Se, Sr, Ta, Ti, V, and Zr.9. The organic light emitting device of claim 1, wherein the hydrogencapturing material includes an element selected from the groupconsisting of Ba, Ca, Cu, Fe, Hf, La, Mg, Nb, Ni, Pd, Pt, Se, Sr, Ta,Ti, V, and Zr.